3.4L project

Eagerly awaiting the UPS guy for my 36mm chokes. The motor has a ton of vacuum is my guess. It's sucking in a lot of fuel so I will drop back a good bit on everything as you suggested and report back. Brilliant, thanks Russ

That tool is too cool. I've been lurking in that thread a bit.

 

Ok folks, I don't have a video yet but I drove the car about an hour ago. Let me tell you, it's transformed the power in every imaginable way, yet remains incredibly docile on the road. The engine behaves like any stock mild mannered engine but has gobs and gobs and gobs more torque and power all over. I have not taken it over 5k rpm but even once the engine is broken in I will see no reason to, it just has so much more power and is incredibly flexible now and........well, it goes genuinely quick and is no longer a slug.

 

I put some miles on the engine over the weekend. Still breaking in the engine so I haven't opened anything up. I can drive it around in 2nd or 3rd gear easily enough. What a fantastic engine though. Incredibly flexible yet I can tell if I really open it up I could spin the rubber of the wheels. Power wise it feels very similar to a '87 Porsche 911 turbo without the lag of course.


Hoping the 36mm chokes show up today. Here's what I'm thinking will happen. The 36mm chokes will decrease the signal to the carbureter causing there to be less 'sucking' through the carb meaning I won't be running as rich with my idle jets and main jets. What's going on with the 32mm chokes is the engine has soooo much vacuum that it's sucking fuel in like crazy and these little stock jets are even too much for most situations. 36mm should clear that up by decreasing the signal. I love carbs, they're such simple creatures.

 

I can give a rough idea. It was about $10k-$11k in parts and machining and 120 hours to do. Easily a $20-$25k Carobu job if they were to do it. And I'm not done. I figure I have another 5.0hrs tuning the thing. I could have blown another $5k installing larger sleeves but I saw absolutely no point to it considering it would give only another 2mm displacement per cylinder.

Justification:
I was at a point a year or so ago where I really wanted a 355 or a 360 but I did not want to deal with their respective 'issues' or their insurance costs. in short, I wanted more Ferrari power. But especially the 355s, ugh I love them but my gosh what a laundry list of 'stuff' to potentially deal with. Now I have a 308 which can easily keep up with either of them and is just a cooler conversation topic of a car, yet most imporantly without the 'issues'.

 

So, two oil leaks. The oil drain plug, and the transmission drain plug. Absolutely none anywhere else. Tight little engine. Going to replace the copper washers again (do this every time you change oil!) and to be paranoid I will put a tiny amount of Curil T on each side of the washer. I want a bone dry garage floor dangit

 

36mm chokes came in yesterday. I of course immediately installed them and went for a drive. No noticeable changes in throttle response or torque. I am definitely going to hash this nonsense out on a dyno though. Idle is still quite rich so I'm going to install size 50 idle jets, although it wouldn't surprise me if I needed to go even smaller.
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Yes, I hate those silly start enrichments.

So, tonight I really dialed in the idle so it idles very smooth now and throttle response is even better.

Total 'all in' ignition timing really wants to be in the 35-36 range and I am progressively programming it in by 5500rpm with most timing coming in by 3k. The engine really responds nicely like this.

Going to reinstall the F24 jets and 140s yet try 220ac and give that a shot. This lump really needs to break in so I can hit the dyno already.....

 

Going leaner and leaner. More airflow = more fuel flow which is directly proportional to air pressure, which of course we have tons more of now. So stock jets on a stock engine will flow completely differently and incredibly rich on an engine which flows tons more air.

So this weekend I am going to try 45 idles with 130 mains and 200 a/c. 55 idles and 140 mains is still wayyyyy too rich but just right on a stock engine. Crazy right.

 

Interesting revelation this morning after a bit of driving and tuning last night. I made the 55 idles work and the car is idling about 13.8:1. The rings must have seated or something between last night and today because the wideband is showing the engine very lean during cruise at 15:1+ while on the main circuit jets. Lots of lean misfire too during the transition. Very interesting as it was never doing this before so I can only assume rings must have seated.

So, I have F36 tubes, 140 mains, 200 a/c in right now. I am going to just swap to F24 tubes and keep the same jets and see how that changes things. The pump jets squirt a ton of fuel in and temporarily bring the mixture down to 10.5:1 so I'm thinking about moving to the next size smaller pump jets just in the name of keeping uniformity when I really hit the gas pedal (I have some sitting in a box anyway). I know F24s really fatten up the mixture a good bit so we'll see how much we get. Might need to bump the mains a bit further even.

 

Once it's broken in and dialed in I will make a vid.

I will say this though. Dollar for dollar a 360 crank combined with these cams is the best $$$ spent on a 2v 308. Absolutely brilliant performing engine. So for anyone considering going a rebuild, for $3500-$4k additional cost on top of the rebuild, you get another bucket-load of bhp making the car a real joy to drive.

 

There is no place online to get them, but they are made by Cat Cams in Belgium. Cat Cams has only one US distributor which is a BMW performance shop called vacmotorsports.com. Ask for Steve. These are a special order item and take about 6 weeks to deliver. Cat Cams website shows the Ferrari Dino cams only, but they do make 308 sets they just aren't listed. The 308 grinds however are the same lobe design as the Dino grinds and specs for these cams are listed on their website. It should be known that a person cannot just email Cat Cams to get cams, we have to go through the US distributor. I guess they loathe dealing with the public lol.

 

I spent a huge amount of time today experimenting with jets and the wideband a/f meter. Now that the rings seem to have broken in, the engine is begging for fuel, especially north of 5k.

Here's what I've tried today and their respective results:

55 idles, F36 emulsion tubes, 150 mains, 220 air correctors: lean transition, lean idle, lean main circuit above 5k, lean cruise

55 idles, F24 emulsion tubes, 150 mains, 220 air correctors: lean transition, reasonable idle, overly rich main circuit over 5k, lean cruise

55 idles, F24 emulsion tubes, 140 mains, 200 air correctors: lean transition, reasonable idle, lean main circuit, lean cruise


Because of the lean transition, I'm thinking I need larger idle jets to richen up the cruise and the idle circuit in general? It's difficult to describe what I'm feeling and seeing in the wideband under by right foot but I'll do my best. While cruising with my foot barely on the accelerator, it's very lean to the point of inducing lean misfire. If I depress the pedal a little more it richens up a good bit and stays rich depending on jetting, or goes lean depending on jetting. But as soon as I go back to 'steady' on the pedal just to maintain speed it goes lean. This is typically taking place under 3500rpm.

The car goes like stink though so I'll keep beating my head against the wall and get this right.


This video is not my car but I kid you not my engine goes the exact same as this one if not faster. It's quite a ride, scroll to 2:09 and you get a good idea of what we're dealing with here. I'll make a vid once this is dialed in. I'm dying here! [ame]http://www.youtube.com/watch?v=pALWwFoHQp0[/ame]

 

Agreed. They are track weapons only yet have an excellent cool factor. Thankfully my engine is a kitten and very easy to drive.

The lean transition is bugging me though. I can dial in a nice idle to around 13.5:1 with about 3.5 turns out but steady cruise with very light throttle application and transition are very lean going up to 16:1 at times. I'm thinking the idle circuit needs to be fatten up with a size 60 idle jet, then I will crank down the idle adjust. Russ, what do you think?

 

Ordered 60 idles. Now the waiting game.....yay.


Question for other carburetor people: When the main circuit kicks in, does the idle transition circuit continue to flow? Or does the pressure all go to the main circuit causing the transition holes to essentially cease flow?

The reason I'm asking this is because I'm wondering if I need to rethink my main jetting once the idle jets are swapped.